// 1、无头单向非循环链表实现
public class SingleLinkedList implements IList{
    static class ListNode {
        public int val;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(head == null){
           head = node;
        }else {
            node.next = head;
            head = node;
        }

    };
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
        }else {
            ListNode cur = head;
            while(cur.next!=null){
               cur = cur.next;
            }
            cur.next = node;
        }
    };
    //任意位置插入,第一个数据节点为0号下标
    public boolean addIndex(int index,int data){
        if(index<0 || index>size()){
            return false;
        }
        if(index == 0){
            addFirst(data);
            return true;
        }
        if(index == size()){
            addLast(data);
            return true;
        }
        ListNode cur = new ListNode(data);
        ListNode node = new ListNode(data);
        while(index != 0){
            cur = head;
            cur = cur.next;
            index--;
        }
        node.next = cur.next;
        cur.next = node;
        return true;

    };
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        if(head == null){
            return false;
        }
        ListNode cur = head;
        while(cur.next != null){
            if(cur.val == key){
                return  true;
            }
            cur = cur.next;
        }
        return false;

    };
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        if(head == null){
            return;
        }
        ListNode cur =head;
        if(cur.val == key){
            head = head.next;
        }
        while(cur.next != null){
            if(cur.next.val == key) break;
            cur = cur.next;
        }
        if(cur.next != null){
            cur.next = cur.next.next;
        }

    };
    //删除所有值为key的节点
    public void removeAllKey(int key){
        if(head == null){
            return;
        }
        ListNode cur =head;
        if(cur.val == key){
            head = head.next;
        }
        while(cur.next != null){
            if(cur.next.val == key) {
                cur.next = cur.next.next;
            }
            cur = cur.next;
        }

    };
    //得到单链表的长度
    public int size(){
        int count = 0;
        ListNode cur = this.head;
        while (cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    };
    public void display(){
        ListNode cur = this.head;
        while (cur != null) {
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    };
    public void clear(){
        ListNode cur = head;
        while (cur != null) {
            ListNode curNext = cur.next;
            //cur.val = null;
            cur.next = null;
            cur = curNext;
        }
        head = null;
    };
}